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  • Should I put actors in the Domain-Model/Class-Diagram?

    - by devoured elysium
    When designing both the domain-model and class-diagrams I am having some trouble understanding what to put in them. I'll give an example of what I mean: I am doing a vacations scheduler program, that has an Administrator and End-Users. The Administrator does a couple of things like registering End-Users in the program, changing their previleges, etc. The End-User can choose his vacations days, etc. I initially defined an Administrator and End-User as concepts in the domain-model, and later as classes in the class-diagram. In the class-diagram, both classes ended up having a couple of methods like Administrator.RegisterNewUser(); Administrator.UnregisterUser(int id); etc. Only after some time I realised that actually both Administrator and End-User are actors, and maybe I got this design totally wrong. Instead of filling Administrator and End-User classes with methods to do what my Use-Cases request, I could define other classes from the domain to do them, and have controllers handle the Use-Cases(actually, I decided to do one for each Use-Case). I could have a UserDatabase.RegisterNewUser() and UserDatabase.UnregisterUser(int id);, for example, instead of having those methods on the Administrator class. The idea would be to try to think of the whole vacation-scheduler as a "closed-program" that has a set of features and doesn't bother with things such as authentication, that should be internal/protected, being that the only public things I'd let the outside world see would be its controllers. Is this the right approach? Or am I getting this totally wrong? Is it generally bad idea to put Actors in the domain-model/class-diagrams? What are good rules of thumb for this? My lecturer is following Applying UML and Patterns, which I find awful, so I'd like to know where I could look up more info on this described actor-models situation. I'm still a bit confused about all of this, as this new approach is radically different from anything I've done before.

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  • CodeIgniter -- unable to use an object

    - by Smandoli
    THE SUMMARY: When I call .../index.php/product, I receive: Fatal error: Call to a member function get_prod_single() on a non-object in /var/www/sparts/main/controllers/product.php on line 16 The offending Line 16 is: $data['pn_oem'] = $this->product_model->get_prod_single($product_id); Looks like I don't know how to make this a working object. Can you help me? THE CODE: In my /Models folder I have product_model.php: <?php class Product_model extends Model { function Product_model() { parent::Model(); } function get_prod_single($product_id) { //This will be a DB lookup ... return 'foo'; //stub to get going } } ?> In my /controllers folder I have product.php: <?php class Product extends Controller { function Product() { parent::Controller(); } function index() { $this->load->model('Product_model'); $product_id = 113; // will get this dynamically $data['product_id'] = $product_id; $data['pn_oem'] = $this->product_model->get_prod_single($product_id); $this->load->view('prod_single', $data); } } ?>

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  • UpdateModelFromDatabaseException when trying to add a table to Entity Framework model

    - by Agent_9191
    I'm running into a weird issue with Entity Framework in .NET 3.5 SP1 within Visual Studio 2008. I created a database with a few tables in SQL Server and then created the associated .edmx Entity Framework model and had no issues. I then created a new table in the database that has a foreign key to an existing table and needed to be added to the .edmx. So I opened the .edmx in Visual Studio and in the models right-clicked and chose "Update Model From Database...". I saw the new table in the "add" tab, so I checked it and clicked finish. However I get an error message with the following text: --------------------------- Microsoft Visual Studio --------------------------- An exception of type 'Microsoft.Data.Entity.Design.Model.Commands.UpdateModelFromDatabaseException' occurred while attempting to update from the database. The exception message is: 'Cannot update from the database. Cannot resolve the Name Target for ScalarProperty 'ID <==> CustomerID'.'. --------------------------- OK --------------------------- For reference, here's the tables seem to be the most pertinent to the error. CustomerPreferences already exists in the .edmx. Diets is the table that was added afterwards and trying to add to the .edmx. CREATE TABLE [dbo].[CustomerPreferences]( [ID] [uniqueidentifier] NOT NULL, [LastUpdatedTime] [datetime] NOT NULL, [LastUpdatedBy] [uniqueidentifier] NOT NULL, PRIMARY KEY CLUSTERED ( [ID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] CREATE TABLE [dbo].[Diets]( [ID] [uniqueidentifier] NOT NULL, [CustomerID] [uniqueidentifier] NOT NULL, [Description] [nvarchar](50) NOT NULL, [LastUpdatedTime] [datetime] NOT NULL, [LastUpdatedBy] [uniqueidentifier] NOT NULL, PRIMARY KEY CLUSTERED ( [ID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] GO ALTER TABLE [dbo].[Diets] WITH CHECK ADD CONSTRAINT [FK_Diets_CustomerPreferences] FOREIGN KEY([CustomerID]) REFERENCES [dbo].[CustomerPreferences] ([ID]) GO ALTER TABLE [dbo].[Diets] CHECK CONSTRAINT [FK_Diets_CustomerPreferences] GO This seems like a fairly common use case, so I'm not sure where I'm going wrong.

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  • Using before_create in Rails to normalize a many to many table

    - by weotch
    I am working on a pretty standard tagging implementation for a table of recipes. There is a many to many relationship between recipes and tags so the tags table will be normalized. Here are my models: class Recipe < ActiveRecord::Base has_many :tag_joins, :as => :parent has_many :tags, :through => :tag_joins end class TagJoin < ActiveRecord::Base belongs_to :parent, :polymorphic => true belongs_to :tag, :counter_cache => :usage_count end class Tag < ActiveRecord::Base has_many :tag_joins, :as => :parent has_many :recipes, :through => :tag_joins, :source => :parent , :source_type => 'Recipe' before_create :normalizeTable def normalizeTable t = Tag.find_by_name(self.name) if (t) j = TagJoin.new j.parent_type = self.tag_joins.parent_type j.parent_id = self.tag_joins.parent_id j.tag_id = t.id return false end end end The last bit, the before_create callback, is what I'm trying to get working. My goal is if there is an attempt to create a new tag with the same name as one already in the table, only a single row in the join table is produced, using the existing row in tags. Currently the code dies with: undefined method `parent_type' for #<Class:0x102f5ce38> Any suggestions?

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  • Parallelizing L2S Entity Retrieval

    - by MarkB
    Assuming a typical domain entity approach with SQL Server and a dbml/L2S DAL with a logic layer on top of that: In situations where lazy loading is not an option, I have settled on a convention where getting a list of entities does not also get each item's child entities (no loading), but getting a single entity does (eager loading). Since getting a single entity also gets children, it causes a cascading effect in which each child then gets its children too. This sounds bad, but as long as the model is not too deep, I usually don't see performance problems that outweigh the benefits of the ease of use. So if I want to get a list in which each of the items is fully hydrated with children, I combine the GetList and GetItem methods. So I'll get a list and then loop through it getting each item with the full cascade. Even this is generally acceptable in many of the projects I've worked on - but I have recently encountered situations with larger models and/or more data in which it needs to be more efficient. I've found that partitioning the loop and executing it on multiple threads yields excellent results. In my first experiment with a list of 50 items from one particular project, I did 5 threads of 10 items each and got a 3X improvement in time. Of course, the mileage will vary depending on the project but all else being equal this is clearly a big opportunity. However, before I go further, I was wondering what others have done that have already been through this. What are some good approaches to parallelizing this type of thing?

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  • Perl Script to search and replace in .SQL query file with user inputs

    - by T.Mount
    I have a .SQL file containing a large number of queries. They are being run against a database containing data for multiple states over multiple years. The machine I am running this on can only handle running the queries for one state, in one year, at a time. I am trying to create a Perl script that takes user input for the state abbreviation, the state id number, and the year. It then creates a directory for that state and year. Then it opens the "base" .SQL file and searches and replaces the base state id and year with the user input, and saves this new .SQL file to the created directory. The current script I have (below) stops at open(IN,'<$infile') with "Can't open [filename]" It seems that it is having difficulty finding or opening the .SQL file. I have quadruple-checked to make sure the paths are correct, and I have even tried replacing the $path with an absolute path for the base file. If it was having trouble with creating the new file I'd have more direction, but since it can't find/open the base file I do not know how to proceed. #!/usr/local/bin/perl use Cwd; $path = getcwd(); #Cleans up the path $path =~ s/\\/\//sg; #User inputs print "What is the 2 letter state abbreviation for the state? Ex. 'GA'\n"; $stlet = <>; print "What is the 2 digit state abbreviation for the state? Ex. '13'\n"; $stdig = <>; print "What four-digit year are you doing the calculations for? Ex. '2008'\n"; $year = <>; chomp $stlet; chomp $stdig; chomp $year; #Creates the directory mkdir($stlet); $new = $path."\/".$stlet; mkdir("$new/$year"); $infile = '$path/Base/TABLE_1-26.sql'; $outfile = '$path/$stlet/$year/TABLE_1-26.sql'; open(IN,'<$infile') or die "Can't open $infile: $!\n"; open(OUT,">$infile2") or die "Can't open $outfile: $!\n"; print "Working..."; while (my $search = <IN>) { chomp $search; $search =~ s/WHERE pop.grp = 132008/WHERE pop.grp = $stdig$year/g; print OUT "$search\n"; } close(IN); close(OUT); I know I also probably need to tweak the regular expression some, but I'm trying to take things one at a time. This is my first Perl script, and I haven't really been able to find anything that handles .SQL files like this that I can understand. Thank you!

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  • Modeling Buyers & Sellers in a Rails Ecommerce App

    - by MikeH
    I'm building a Rails app that has Etsy.com style functionality. In other words, it's like a mall. There are many buyers and many sellers. I'm torn about how to model the sellers. Key facts: There won't be many sellers. Perhaps less than 20 sellers in total. There will be many buyers. Hopefully many thousands :) I already have a standard user model in place with account creation and roles. I've created a 'role' of 'seller', which the admin will manually apply to the proper users. Since we'll have very few sellers, this is not an issue. I'm considering two approaches: (1) Create a 'store' model, which will contain all the relevant store information. Products would :belong_to :store, rather than belonging to the seller. The relationship between the user and store models would be: user :has_one store. My main problem with this is that I've always found has_one associations to be a little funky, and I usually try to avoid them. The app is fairly complex, and I'm worried about running into a cascade of problems connected to the has_one association as I get further along into development. (2) Simply include the relevant 'store' information as part of the user model. But in this case, the store-related db columns would only apply to a very small percentage of users since very few users will also be sellers. I'm not sure if this is a valid concern or not. It's very possible that I'm thinking about this incorrectly. I appreciate any thoughts. Thanks.

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  • How do I form a Rails link_to with custom field value as parameter

    - by rwheadon
    I have an invoice form where I'm giving the user opportunity to apply coupons to the invoice total. These coupons are held in another Model and I am going to do a lookup on the Coupon code (something like "20OFFONFRIDAY") which I will use to find what the restrictions and benefits of the coupon. (and to see if it even exists at all) The invoice does not have "coupon_code" on it so I hand forged the field onto my form with html: <% if (@invoice.status == 'new') %> <input id="coupon_code" name="coupon_code" type="text"/> <% end %> and I am calling a controller method with link_to and would like something like the following jquery enhanced link_to to work: <%= link_to "Apply Coupon", { :controller=>"invoices", :id=>@invoice.id, :coupon_code=>$('.coupon_code').val(), :action=>"apply_coupon_code" }, :method=>"post" %> ^formatted for easier reading Then inside my "apply_coupon_code" method I will go off to a couple other models and perform business logic before returning the updated invoice page. ...but maybe it's a pipe dream. I guess if push came to shove I could add the "coupon_code" field to my invoice model (even though it's persisted elsewhere.) so it's part of the entity and thus easily available on my form to send back into a controller, but I just hate adding a column to make a coupon validation easier. I figured I'd ping stackoverflow before taking that path.

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  • STI and accepts_nested_attributes_for in rails

    - by ryanshackintosh
    I have models as follows: class Entity < ActiveRecord::Base has_many :addresses accepts_nested_attributes_for :addresses, :reject_if => lambda { |a| a[:label].blank?} , :allow_destroy => true end class Client < Entity before_save :set_type private def set_type self.type = "Client" end end class Address < ActiveRecord::Base belongs_to :entity end I have recently implemented accepts_nested_attributes_for on the /clients/new form, as follows: <% form_for(@client, :html => {:class => 'form'}) do |f| -%> <%= f.label :name %> <%= f.text_field :name -%> <%= f.label :phone %> <%= f.text_field :phone %> <% f.fields_for :addresses do |a| %> <%= a.label :street %> <%= a.text_field :street%> <%= a.label :city %> <%= a.text_field :city %> <% end %> <% end %> And my controller as follows: class ClientsController < ApplicationController before_filter :load_client , :except => [:index, :new, :create, :render_clients] def new @client = Client.new @client.addresses.build end def create @client = Client.new(params[:client]) if @client.save flash[:notice] = 'Client has been successfully added' redirect_to @client else render :action => 'new' end end The issue is that when the record is saved it gives an error stating: "Entity can't be blank" I assume it is something to do with the fact that a 'Client' and not an 'Entity' is being added. Can anyone point me in the right direction?

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  • Best practices for "search data class" in ASP.NET MVC

    - by Tim Ridgely
    Hi everybody, I'm hoping this isn't too subjective, but I'm new to ASP.NET MVC and I'm trying to figure out how others may have solved similar problems. Basically, I have two entities, Customers and Orders. A customer has many orders; an order belongs to exactly one customer. I'm making an Order Search feature that should allow a user to search for orders based on order or customer information. Pretty straightforward, I think. I've read in other posts that the search controller should use GET, but I think it makes more sense to use POST because of the large number of search params. I'm using Entity Framework to create my models, and that's in a separate class library project and namespace. This article talks about using binding instead of Request.Form to get at the POST data. Would it make decent sense to make a class to hold all the search data that could be materialized by the magic model binding? Otherwise I'd just be poking through the FormCollection to pull out particular values, which might be fine. Where would you recommend making such a class?

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  • CakePHP - recursive on specific fields in model?

    - by Paul
    Hi, I'm pretty new to CakePHP but I think I'm starting to get the hang of it. I'm trying to pull related table information recursively, but I want to specify which related models to recurse on. Let me give you an example to demonstrate my goal: I have a model "Customer", which has info like Company name, website, etc. "Customer" hasMany "Addresses", which contain info for individual contacts like Contact Name, Street, City, State, Country, etc. "Customer" also belongsTo "CustomerType", which is just has descriptive category info - a name and description, like "Distributor" or "Manufacturer". When I do a find on "Customer" I want to get associated "CustomerType" and "Address" info as sub-arrays, and this works fine just by setting up the hasMany and belongsTo associations properly. But now, here's my issue: I want to get associated State/Country info. So, instead of each "Address" array row just having "state_id", I want it to have "state" = array("id" = 20, "name" = "New York",...) etc. If I set $recursive to a higher value (e.g., 2) in the Partner model, I get what I want for the State/Country info in each "Address". BUT it also recurses on "CustomerType", and that results in the "CustomerType" field of my "Partner" object having a huge array of all Customer objects that match that type, which could be thousands long. So the point is, I DON'T want to recurse on "CustomerType", only on "Address". Is there a way I can set this up? Sorry for the long-winded question, and thanks in advance!

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  • Doctrine YAML not generating correctly? Or is this markup wrong?

    - by ropstah
    I'm trying to get a many-to-many relationship between Users and Settings. The models seem to be generated correctly, however the following query fails: "User_Setting" with an alias of "us" in your query does not reference the parent component it is related to. $q = new Doctrine_RawSql(); $q->select('{s.*}, {us.*}') ->from('User u CROSS JOIN Setting s LEFT JOIN User_Setting us ON us.usr_auto_key = u.usr_auto_key AND us.set_auto_key = s.set_auto_key') ->addComponent('s', 'Setting s INDEXBY s.set_auto_key') ->addComponent('us', 'User_Setting us') ->where(u.usr_auto_key = ?',$this->usr_auto_key); $this->settings = $q->execute(); Does anyone spot a problem? This is my YAML: User: connection: default tableName: User columns: usr_auto_key: type: integer(4) fixed: false unsigned: false primary: true autoincrement: true notnull: true email: type: string(100) fixed: false unsigned: false primary: false default: '' notnull: true autoincrement: false password: type: string(32) fixed: false unsigned: false primary: false default: '' notnull: true autoincrement: false relations: Setting: class: Setting foreignAlias: User refClass: User_Setting local: usr_auto_key foreign: set_auto_key Setting: connection: default tableName: Setting columns: set_auto_key: type: integer(4) fixed: false unsigned: false primary: true autoincrement: true notnull: true name: type: string(50) fixed: false unsigned: false primary: false notnull: true autoincrement: false User_Setting: connection: default tableName: User_Setting columns: usr_auto_key: type: integer(4) fixed: false unsigned: false primary: true autoincrement: false notnull: true set_auto_key: type: integer(4) fixed: false unsigned: false primary: true autoincrement: false notnull: true value: type: string(255) fixed: false unsigned: false primary: false notnull: true autoincrement: false relations: Setting: foreignAlias: User_Setting local: set_auto_key foreign: set_auto_key User: foreignAlias: User_Setting local: usr_auto_key foreign: usr_auto_key

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  • Rails - Create if record doesn't exist or else update.....Whats Best way to do this?

    - by ChrisWesAllen
    Hi, I have a create statement for some models but its creating a record within a join table regardless if the record exist. Here is what my code looks like. @user = User.find(current_user) @event = Event.find(params[:id]) for interest in @event.interests @user.choices.create(:interest => interest, :score => 4) end The problem is it creates records no matter what. I would like it to create a record if it doesnt exist, if a record does exist I would just to it to take the attribute of the found record and add or subtract 1. So, I've been looking around and I see something called find_or_create_by. My question is what happens if it finds? Preferably if it finds,I would like to take the current :score attribute and +1. SO is it possible to find or create by id? I'm not sure what attribute I would find by since the model I'm looking at is a join model which only had id foreign keys and the score attribute. I tried @user.choices.find_or_create_by_user(:user => @user.id, :interest => interest, :score => 4) but got "undefined method `find_by_user'".....ANy ideas or help?

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  • Two references to the same domain/entity model

    - by Sbossb
    Problem I want to save the attributes of a model that have changed when a user edits them. Here's what I want to do ... Retrieve edited view model Get domain model and map back updated value Call the update method on repository Get the "old" domain model and compare values of the fields Store the changed values (in JSON) into a table However I am having trouble with step number 4. It seems that the Entity Framework doesn't want to hit the database again to get the model with the old values. It just returns the same entity I have. Attempted Solutions I have tried using the Find() and the SingleOrDefault() methods, but they just return the model I currently have. Example Code private string ArchiveChanges(T updatedEntity) { //Here is the problem! //oldEntity is the same as updatedEntity T oldEntity = DbSet.SingleOrDefault(x => x.ID == updatedEntity.ID); Dictionary<string, object> changed = new Dictionary<string, object>(); foreach (var propertyInfo in typeof(T).GetProperties()) { var property = typeof(T).GetProperty(propertyInfo.Name); //Get the old value and the new value from the models var newValue = property.GetValue(updatedEntity, null); var oldValue = property.GetValue(oldEntity, null); //Check to see if the values are equal if (!object.Equals(newValue, oldValue)) { //Values have changed ... log it changed.Add(propertyInfo.Name, newValue); } } var ser = new System.Web.Script.Serialization.JavaScriptSerializer(); return ser.Serialize(changed); } public override void Update(T entityToUpdate) { //Do something with this string json = ArchiveChanges(entityToUpdate); entityToUpdate.AuditInfo.Updated = DateTime.Now; entityToUpdate.AuditInfo.UpdatedBy = Thread.CurrentPrincipal.Identity.Name; base.Update(entityToUpdate); }

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  • Potential Django Bug In QuerySet.query?

    - by Mike
    Disclaimer: I'm still learning Django, so I might be missing something here, but I can't see what it would be... I'm running Python 2.6.1 and Django 1.2.1. (InteractiveConsole) >>> from myproject.myapp.models import * >>> qs = Identifier.objects.filter(Q(key="a") | Q(key="b")) >>> print qs.query SELECT `app_identifier`.`id`, `app_identifier`.`user_id`, `app_identifier`.`key`, `app_identifier`.`value` FROM `app_identifier` WHERE (`app_identifier`.`key` = a OR `app_identifier`.`key` = b ) >>> Notice that it doesn't put quotes around "a" or "b"! Now, I've determined that the query executes fine. So, in reality, it must be doing so. But, it's pretty annoying that printing out the query prints it wrong. Especially if I did something like this... >>> qs = Identifier.objects.filter(Q(key=") AND") | Q(key="\"x\"); DROP TABLE `app_identifier`")) >>> print qs.query SELECT `app_identifier`.`id`, `app_identifier`.`user_id`, `app_identifier`.`key`, `app_identifier`.`value` FROM `app_identifier` WHERE (`app_identifier`.`key` = ) AND OR `app_identifier`.`key` = "x"); DROP TABLE `app_identifier` ) >>> Which, as you can see, not only creates completely malformed SQL code, but also has the seeds of a SQL injection attack. Now, obviously this wouldn't actually work, for quite a number of reasons (1. The syntax is all wrong, intentionally, to show the oddity of Django's behavior. 2. Django won't actually execute the query like this, it will actually put quotes and slashes and all that in there like it's supposed to). But, this really makes debugging confusing, and it makes me wonder if something's gone wrong with my Django installation. Does this happen for you? If so/not, what version of Python and Django do you have? Any thoughts?

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  • Why is my rspec test failing?

    - by Justin Meltzer
    Here's the test: describe "admin attribute" do before(:each) do @user = User.create!(@attr) end it "should respond to admin" do @user.should respond_to(:admin) end it "should not be an admin by default" do @user.should_not be_admin end it "should be convertible to an admin" do @user.toggle!(:admin) @user.should be_admin end end Here's the error: 1) User password encryption admin attribute should respond to admin Failure/Error: @user = User.create!(@attr) ActiveRecord::RecordInvalid: Validation failed: Email has already been taken # ./spec/models/user_spec.rb:128 I'm thinking the error might be somewhere in my data populator code: require 'faker' namespace :db do desc "Fill database with sample data" task :populate => :environment do Rake::Task['db:reset'].invoke admin = User.create!(:name => "Example User", :email => "[email protected]", :password => "foobar", :password_confirmation => "foobar") admin.toggle!(:admin) 99.times do |n| name = Faker::Name.name email = "example-#{n+1}@railstutorial.org" password = "password" User.create!(:name => name, :email => email, :password => password, :password_confirmation => password) end end end Please let me know if I should reproduce any more of my code. UPDATE: Here's where @attr is defined, at the top of the user_spec.rb file: require 'spec_helper' describe User do before(:each) do @attr = { :name => "Example User", :email => "[email protected]", :password => "foobar", :password_confirmation => "foobar" } end

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  • Where to start with the development of first database driven Web App (long question)?

    - by Ryan
    Hi all, I've decided to develop a database driven web app, but I'm not sure where to start. The end goal of the project is three-fold: 1) to learn new technologies and practices, 2) deliver an unsolicited demo to management that would show how information that the company stores as office documents spread across a cumbersome network folder structure can be consolidated and made easier to access and maintain and 3) show my co-workers how Test Drive Development and prototyping via class diagrams can be very useful and reduces future maintenance headaches. I think this ends up being a basic CMS to which I have generated a set of features, see below. 1) Create a database to store the site structure (organized as a tree with a 'project group'-project structure). 2) Pull the site structure from the database and display as a tree using basic front end technologies. 3) Add administrator privileges/tools for modifying the site structure. 4) Auto create required sub pages* when an admin adds a new project. 4.1) There will be several sub pages under each project and the content for each sub page is different. 5) add user privileges for assigning read and write privileges to sub pages. What I would like to do is use Test Driven Development and class diagramming as part of my process for developing this project. My problem; I'm not sure where to start. I have read on Unit Testing and UML, but never used them in practice. Also, having never worked with databases before, how to I incorporate these items into the models and test units? Thank you all in advance for your expertise.

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  • When calling a static method on parent class, can the parent class deduce the type on the child (C#)

    - by Matt
    Suppose we have 2 classes, Child, and the class from which it inherits, Parent. class Parent { public static void MyFunction(){} } class Child : Parent { } Is it possible to determine in the parent class how the method was called? Because we can call it two ways: Parent.MyFunction(); Child.MyFunction(); My current approach was trying to use: MethodInfo.GetCurrentMethod().ReflectedType; // and MethodInfo.GetCurrentMethod().DeclaringType; But both appear to return the Parent type. If you are wondering what, exactly I am trying to accomplish (and why I am violating the basic OOP rule that the parent shouldn't have to know anything about the child), the short of it is this (let me know if you want the long version): I have a Model structure representing some of our data that persists to the database. All of these models inherit from an abstract Parent. This parent implements a couple of events, such as SaveEvent, DeleteEvent, etc. We want to be able to subscribe to events specific to the type. So, even though the event is in the parent, I want to be able to do: Child.SaveEvent += new EventHandler((sender, args) => {}); I have everything in place, where the event is actually backed by a dictionary of event handlers, hashed by type. The last thing I need to get working is correctly detecting the Child type, when doing Child.SaveEvent. I know I can implement the event in each child class (even forcing it through use of abstract), but it would be nice to keep it all in the parent, which is the class actually firing the events (since it implements the common save/delete/change functionality).

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  • What's a good way to format AJAX responses? Or, using Django templating with AJAX

    - by synic
    In some of the code I'm working on, the author max AJAX calls to a Django view that returns JSON. Once the JSON is retrieved, it'll be injected into the page with a function that looks like this (note, this is a simplification, but I'm sure you know what I'm getting at here): function build_event_listing(events) { var html = ''; for(int i = 0; i < events.length; i++) { event = events[i]; html += "<h2>" + event.title + "</h2>\n"; html += "<p>" + event.description + "</p>"; html += "Click <a href='/event/view/" + event.id + "'>here<a> for more info."; } events_div.html(html); } I really don't like this approach. To change the look of each event listing, the designer would have to modify that ugly JS. I'd much rather make use of Django's templating system, but I'm wondering how I can do this? I had the idea of writing the view like this: def view_listings(req): events = models.Event.objects.all() html = [] for event in events: html.append( render_to_string('event/single_event.html', { 'event': event, }, context_instance=RequestContext(req)) return HttpResponse(''.join(html), mimetype='text/html') ... but it just seems like there should be a better way. Any ideas?

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  • Saving a Record with Rails Association

    - by tshauck
    Hi, I've been going through the Rails Guides, but have gotten stuck on associations after going through validations and migrations. So, I have the following models Job and Person, where a Person can have many jobs. I know that in reality there'd be a many-to-many, but I'm trying to get my handle on this first. class Job < ActiveRecord::Base belongs_to :people end and class Person < ActiveRecord::Base has_many :jobs end Here's the schema ActiveRecord::Schema.define(:version => 20110108185924) do create_table "jobs", :force => true do |t| t.string "occupation" t.boolean "like" t.datetime "created_at" t.datetime "updated_at" t.integer "person_id" end create_table "people", :force => true do |t| t.string "first_name" t.string "last_name" t.datetime "created_at" t.datetime "updated_at" end end Is there some I can do the following j = Job.first; j.Person? Then that'd give me access to the Person object associated with the j. I couldn't find it on guides.rubyonrails.org, although it has been very helpful getting a grip on migrations and validations thus far. Thanks PS, If there are any tutorials that covers more of this kind of things links would be great.

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  • Looking for a book which teaches how to write applications (as opposed to writng code)

    - by rumtscho
    I am not a developer. I have coded for fun and for university projects in several languages, and during an internship, I have written code which is still in use by a department of Fortune Global 500 company. I also have extensive theoretical knowledge of software engineering - process models, architecture, project management, UI construction using Lauesen's virtual windows... you get the picture. But I am not involved with software development in my job. I recently decided to start coding for fun again, and now I have some free days to do it. But this time, I want to do it right. I want to write a real, useful application, install it on my devices and use it myself. Also I want to publish it for others to use, should they want to do so. I am vaguely aware that there is more to writing an application than to writing code. There is stuff like version control software, decision for the right IDE, having a suite of unit tests, producing an installation package - and probably lots of other things I never thought of but which must be taken care of in a proper application, as opposed to a bunch of classes I am running from my IDE. All this is stuff I should know before I start, but I have not learned it. Coding books touch on some of the subjects like IDE choice, but don't go into detail, and are not exhaustive. Theoretical software engineering textbooks are even less helpful. So is there a book which teaches exactly that? I know that I can find information on each of these topics on the Internet, but I'd rather have a systematic book exhaustively listing all the things I should take care of if I want to create a good application, and offering the currently accepted solutions for them. In the best case, it will be language- and platform independent, but if you know of a good book focusing on a specific platform, I would like to know about it too. I know I want a lot, but given how important such knowledge is and how many people need it, surely somebody must have written such a book?

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  • Creating nested fields for column on assignment table?

    - by H O
    I have three models, that represent a many to many relationship - Product, Sale and Product_sale. I have a nested form that allows me to create new products from the sale form - so far, so good. I have, however, added some additional fields to the assignment table - price, for example. How can I set the price on the assignment table from the product form, when it is nested in the sale form? I currently have the code below: <%= sale.fields_for :products do |products_builder| %> <%= render :partial => "products/form", :locals => {:f => products_builder, :form_actions_visible => false} %> <% end -%> I could nest a Product_sale form within the product form, but this would create a new product_sale, which is not what I am looking for. I will most likely need to nest the price field within the product form, to ensure that it updates the correct assignment record (since there could be multiple products on one sale form). How can I use a fields_for loop on the product form to update the existing assignment record that is built when I do @sale.products.build? The assignment record will not yet be saved, so I can not access it using a where clause and edit it that way. Thanks!

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  • How with lambda function in MVC3

    - by doogdeb
    I have a model which contains view models for each view. This model is held in session and is initialised when application starts. I need to be able to populate a field from one view model with the value from another so have used a lambda function. Below is my model. I am using a lambda so that when I get Test2.MyProperty it will use the FunctionTestProperty to retrieve the value from Test1.TestProperty. public class Model { public Model() { Test1 = new Test1() Test2 = new Test2(FunctionTestProperty () => Test1.TestProperty) } } public class Test1 { public string TestProperty { get; set; } } public class Test2 { public Test2() : this (() => string.Empty) {} public Test2(Func<string> functionTestProperty) { FunctionTestProperty = functionTestProperty; } public Func<string> FunctionTestProperty { get; set; } public string MyProperty { get{ return FunctionTestProperty() ?? string.Empty; } } } This works perfectly when I first run the application and navigate from Test1 to Test2; I can see that when I get the value for MyProperty it calls back to Model constructor and retrieves the Test1.TestProperty value. However when I then submit the form (Test2) it calls the default constructor which sets it to string.Empty. So if I go back to Test1 and back to Test2 again it always then calls the Test2 default constructor. Does anyone know why this works when first running the application but not after the view is submitted, or if I have made an obvious mistake?

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  • Extending the CI_DB_active_record class in codeigniter 2.0

    - by ctrane
    I am writing my first program with Codeigniter, and have run into a problem. I will start with a focused description of the problem and can broaden it if I need to: I need to write a multi-dimensional array to the DB and want to use the insert_batch function from the CI_DB_active_record class to do so. The problem is that I need to write empty values as NULL for some fields while other fields need to be empty strings. The current function wraps all values with single quotes, and I cannot find a way to write null values to the database for specified fields. I would also like to increase the number of records per batch. I see how to extend models, libraries, etc., but is there a way to extend the CI_DB_active_record class without modifying core classes? The minimal amount of core class modification to make this work that I have found is modifying the following lines in the DB.php file (changing the require_once file to the new file that extends the CI_DB_active_record class and changing the CI_DB_active_record class name to the new class name): require_once(BASEPATH.'database/DB_active_rec'.EXT); if ( ! class_exists('CI_DB')) { eval('class CI_DB extends CI_DB_active_record { }'); } Can I do better?

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  • [Rails] Accessing error_messages on form_tag

    - by aaronrussell
    I have built a custom form for creating a joining model on a has_many :through relationship. The models look roughly like this: class Team has_many :team_members has_many :members, :through => :team_members end class Member has_many :team_members has_many :teams, :through => :team_members end class TeamMember belongs_to :team belongs_to :member # and this model has some validations too end The form I have built is for selecting which members should be in a team. I won't paste the form, but it uses the form_tag method and basically sends an array of hashes which contain a member_id and a squad_number. I then update the database with an action that looks roughly like this (simplified a bit, but you get the jist): @team.transaction do @team.team_members = params[:team_members].collect{|tm| @team.team_members.new(tm)} if @team.save redirect_to ... else render :action => :members end end Everything works great but I am validating the squad_number for uniqueness and numerically. So, when any of those validations fail, how do I get access to them in my view, and how do I ascertain which of the many members it has failed on?

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